Ok I think I maybe narrowing it down, those of you who are "Rebooting" you are most likely restarting Sense and not rebooting. Those that are powering off completely, I suspect there is voltage error. What kind of battery life are you getting out of your phone? Personally I would RMA asap.
I think it's not just restarting sense but rather a full reboot. It takes a good minute or more for the phone to be ready to use again, just as if it had been shut down and turned back on.